1
|
Li L, Liu MS, Li GQ, Tang J, Liao Y, Zheng Y, Guo TL, Kang X, Yuan MT. Relationship between Apolipoprotein Superfamily and Parkinson's Disease. Chin Med J (Engl) 2018; 130:2616-2623. [PMID: 29067960 PMCID: PMC5678263 DOI: 10.4103/0366-6999.217092] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Objective: Parkinson's disease (PD) is featured with motor disorder and nonmotor manifestations including psychological symptoms, autonomic nervous system dysfunction, and paresthesia, which results in great inconvenience to the patients’ life. The apolipoprotein (Apo) superfamily, as a group of potentially modifiable biomarkers in clinical practice, is of increasing significance in the diagnosis, evaluation, and prognosis of PD. The present review summarized the current understanding and emerging findings of the relationship between Apo superfamily and PD. Data Sources: All literatures were identified by systematically searching PubMed, Embase, and Cochrane electronic databases with terms “Parkinson disease,” “apolipoprotein,” and their synonyms until May 2017. Study Selection: We have thoroughly examined titles and abstracts of all the literatures that met our search strategy and the full text if the research is identified or not so definite. Reference lists of retrieved articles were also scrutinized for additional relevant studies. Results: The levels of plasma ApoA1 are inversely correlated with the risk of PD and the lower levels of ApoA1 trend toward association with poorer motor performance. Higher ApoD expression in neurons represents more puissant protection against PD, which is critical in delaying the neurodegeneration process of PD. It is suggested that APOE alleles are related to development and progression of cognitive decline and age of PD onset, but conclusions are not completely identical, which may be attributed to different ApoE isoforms. APOJ gene expressions are upregulated in PD patients and it is possible that high ApoJ level is an indicator of PD dementia and correlates with specific phenotypic variations in PD. Conclusions: The Apo superfamily has been proved to be closely involved in the initiation, progression, and prognosis of PD. Apos and their genes are of great value in predicting the susceptibility of PD and hopeful to become the target of medical intervention to prevent the onset of PD or slow down the progress. Therefore, further large-scale studies are warranted to elucidate the precise mechanisms of Apos in PD.
Collapse
Affiliation(s)
- Lin Li
- Department of Neurology, The First Affiliated Hospital, Chongqing Medical University, Chongqing 400016, China
| | - Ming-Su Liu
- Department of Neurology, The First Affiliated Hospital, Chongqing Medical University, Chongqing 400016, China
| | - Guang-Qin Li
- Department of Neurology, The First Affiliated Hospital, Chongqing Medical University, Chongqing 400016, China
| | - Jie Tang
- Department of Neurology, The First Affiliated Hospital, Chongqing Medical University, Chongqing 400016, China
| | - Yan Liao
- Department of Neurology, The First Affiliated Hospital, Chongqing Medical University, Chongqing 400016, China
| | - Yang Zheng
- Department of Neurology, The First Affiliated Hospital, Chongqing Medical University, Chongqing 400016, China
| | - Tong-Li Guo
- Department of Neurology, The First Affiliated Hospital, Chongqing Medical University, Chongqing 400016, China
| | - Xin Kang
- Department of Neurology, The First Affiliated Hospital, Chongqing Medical University, Chongqing 400016, China
| | - Mao-Ting Yuan
- Department of Neurology, The First Affiliated Hospital, Chongqing Medical University, Chongqing 400016, China
| |
Collapse
|
2
|
High dietary arachidonic acid levels induce changes in complex lipids and immune-related eicosanoids and increase levels of oxidised metabolites in zebrafish (Danio rerio). Br J Nutr 2017; 117:1075-1085. [PMID: 28485254 PMCID: PMC5481881 DOI: 10.1017/s0007114517000903] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
This study explores the effect of high dietary arachidonic acid (ARA) levels (high ARA) compared with low dietary ARA levels (control) on the general metabolism using zebrafish as the model organism. The fatty acid composition of today's 'modern diet' tends towards higher n-6 PUFA levels in relation to n-3 PUFA. Low dietary n-3:n-6 PUFA ratio is a health concern, as n-6 PUFA give rise to eicosanoids and PG, which are traditionally considered pro-inflammatory, especially when derived from ARA. Juvenile zebrafish fed a high-ARA diet for 17 d had a lower whole-body n-3:n-6 PUFA ratio compared with zebrafish fed a low-ARA (control) diet (0·6 in the control group v. 0·2 in the high-ARA group). Metabolic profiling revealed altered levels of eicosanoids, PUFA, dicarboxylic acids and complex lipids such as glycerophospholipids and lysophospholipids as the most significant differences compared with the control group. ARA-derived hydroxylated eicosanoids, such as hydroxy-eicosatetraenoic acids, were elevated in response to high-ARA feed. In addition, increased levels of oxidised lipids and amino acids indicated an oxidised environment due to n-6 PUFA excess in the fish. To conclude, our results indicate that an ARA-enriched diet induces changes in complex lipids and immune-related eicosanoids and increases levels of oxidised lipids and amino acids, suggesting oxidative stress and lipid peroxidation.
Collapse
|
3
|
Leis HJ, Windischhofer W. Calcium-independent phospholipases A2 in murine osteoblastic cells and their inhibition by bromoenol lactone: impact on arachidonate dynamics and prostaglandin synthesis. J Enzyme Inhib Med Chem 2015; 31:1203-13. [PMID: 26609885 DOI: 10.3109/14756366.2015.1114929] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
CONTEXT Bromoenol lactone (BEL) is an inhibitor of group VI phospholipases (iPLA2s), but has been shown to have severe side effects. OBJECTIVE iPLA2 characterization in osteoblasts and effect of BEL on prostaglandin (PG) E2 formation. METHODS iPLA2 expression: RT-PCR, Western Blotting. PGE2 formation: GC-MS after stimulation, treatment with inhibitors or gene silencing. Arachidonate (AA) reacylation into phospholipids, inhibitor reaction products, PGHS-1 modification proteomic analysis: HR-LC-MS/MS. AA accumulation: (14)C-AA. RESULTS iPLA2ß and iPLA2γ were expressed and functionally active. BEL inhibition up to 20 μM caused AA accumulation and enhanced PGE2 formation, followed by a decrease at higher concentrations. BEL reacted with intracellular cysteine and GSH leading to GSH depletion and oxidative stress. DISCUSSION Initial PGE2 enhancement after BEL inhibition is due to iPLA2-independent accumulation of AA. GSH depletion caused by high BEL concentrations is responsible for the decrease in PGE2 production. CONCLUSION BEL must be used with caution in a cellular environment due to conditions of extreme oxidative stress.
Collapse
Affiliation(s)
- Hans Jörg Leis
- a University Hospital of Youth and Adolescence Medicine, Medical University of Graz, Research Unit of Analytical Mass Spectrometry, Cell Biology and Biochemistry of Inborn Errors of Metabolism , Graz , Austria
| | - Werner Windischhofer
- a University Hospital of Youth and Adolescence Medicine, Medical University of Graz, Research Unit of Analytical Mass Spectrometry, Cell Biology and Biochemistry of Inborn Errors of Metabolism , Graz , Austria
| |
Collapse
|
4
|
Abstract
It is becoming increasingly clear that neurological diseases are multi-factorial involving disruptions in multiple cellular systems. Thus, while each disease has its own initiating mechanisms and pathologies, certain common pathways appear to be involved in most, if not all, neurological diseases. Thus, it is unlikely that modulating only a single factor will be effective at either preventing disease development or slowing disease progression. A better approach is to identify small (< 900 daltons) molecules that have multiple biological activities relevant to the maintenance of brain function. We have identified an orally active, novel neuroprotective and cognition-enhancing molecule, the flavonoid fisetin. Fisetin not only has direct antioxidant activity but it can also increase the intracellular levels of glutathione, the major intracellular antioxidant. Fisetin can also activate key neurotrophic factor signaling pathways. In addition, it has anti-inflammatory activity and inhibits the activity of lipoxygenases, thereby reducing the production of pro-inflammatory eicosanoids and their by-products. This wide range of actions suggests that fisetin has the ability to reduce the impact of age-related neurological diseases on brain function.
Collapse
Affiliation(s)
- Pamela Maher
- The Salk Institute for Biological Studies, 10010 N. Torrey Pines Rd, La Jolla, CA 92037,
| |
Collapse
|
5
|
Sun L, Xu YW, Han J, Liang H, Wang N, Cheng Y. 12/15-Lipoxygenase metabolites of arachidonic acid activate PPARγ: a possible neuroprotective effect in ischemic brain. J Lipid Res 2015; 56:502-514. [PMID: 25605873 DOI: 10.1194/jlr.m053058] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The enzyme 12/15-lipoxygenase (LOX) oxidizes various free fatty acids, including arachidonic acid (AA). In the brain, the principal 12/15-LOX metabolites of AA are 12(S)-HETE and 15(S)-HETE. PPARγ is a nuclear receptor whose activation is neuroprotective through its anti-inflammatory properties. In this study, we investigate the involvement of 12(S)- and 15(S)-HETE in the regulation of PPARγ following cerebral ischemia and their effects on ischemia-induced inflammatory response. We show here the increased expression of 12/15-LOX, predominantly in neurons, and elevated production of 12(S)-HETE and 15(S)-HETE in ischemic brain. The exogenous 12(S)- and 15(S)-HETE increase PPARγ protein level, nuclear translocation, and DNA-binding activity in ischemic rats, suggesting the activation of PPARγ. This effect was further confirmed by showing the increased PPARγ transcriptional activity in primary cortical neurons when incubated with 12(S)- or 15(S)-HETE. Moreover, both 12(S)- and 15(S)-HETE potently inhibited the induction of nuclear factor-κB, inducible NO synthase, and cyclooxygenase-2 in ischemic rats, and elicited neuroprotection. The reversal of the effects of 12(S)- and 15(S)-HETE on pro-inflammatory factors by PPARγ antagonist GW9662 indicated their actions were mediated via PPARγ. Thus, the induction of 12(S)- and 15(S)-HETE during brain ischemia suggests that endogenous signals of neuroprotection may be generated.
Collapse
Affiliation(s)
- Li Sun
- Tianjin Medical University General Hospital, Tianjin Neurological Institute, Key Laboratory of Post-trauma Neuro-repair and Regeneration in Central Nervous System, Ministry of Education, Tianjin Key Laboratory of Injuries, Variations and Regeneration of Nervous System, Tianjin, 300052, People's Republic of China.
| | - Yan-Wei Xu
- Tianjin Medical University General Hospital, Tianjin Neurological Institute, Key Laboratory of Post-trauma Neuro-repair and Regeneration in Central Nervous System, Ministry of Education, Tianjin Key Laboratory of Injuries, Variations and Regeneration of Nervous System, Tianjin, 300052, People's Republic of China
| | - Jing Han
- Tianjin Medical University General Hospital, Tianjin Neurological Institute, Key Laboratory of Post-trauma Neuro-repair and Regeneration in Central Nervous System, Ministry of Education, Tianjin Key Laboratory of Injuries, Variations and Regeneration of Nervous System, Tianjin, 300052, People's Republic of China
| | - Hao Liang
- Tianjin Medical University General Hospital, Tianjin Neurological Institute, Key Laboratory of Post-trauma Neuro-repair and Regeneration in Central Nervous System, Ministry of Education, Tianjin Key Laboratory of Injuries, Variations and Regeneration of Nervous System, Tianjin, 300052, People's Republic of China
| | - Ning Wang
- Tianjin Medical University General Hospital, Tianjin Neurological Institute, Key Laboratory of Post-trauma Neuro-repair and Regeneration in Central Nervous System, Ministry of Education, Tianjin Key Laboratory of Injuries, Variations and Regeneration of Nervous System, Tianjin, 300052, People's Republic of China
| | - Yan Cheng
- Tianjin Medical University General Hospital, Tianjin Neurological Institute, Key Laboratory of Post-trauma Neuro-repair and Regeneration in Central Nervous System, Ministry of Education, Tianjin Key Laboratory of Injuries, Variations and Regeneration of Nervous System, Tianjin, 300052, People's Republic of China
| |
Collapse
|
6
|
Chou VP, Holman TR, Manning-Bog AB. Differential contribution of lipoxygenase isozymes to nigrostriatal vulnerability. Neuroscience 2012; 228:73-82. [PMID: 23079635 DOI: 10.1016/j.neuroscience.2012.10.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 10/03/2012] [Accepted: 10/04/2012] [Indexed: 02/05/2023]
Abstract
The 5- and 12/15-lipoxygenase (LOX) isozymes have been implicated to contribute to disease development in CNS disorders such as Alzheimer's disease. These LOX isozymes are distinct in function, with differential effects on neuroinflammation, and the impact of the distinct isozymes in the pathogenesis of Parkinson's disease has not as yet been evaluated. To determine whether the isozymes contribute differently to nigrostriatal vulnerability, the effects of 5- and 12/15-LOX deficiency on dopaminergic tone under naïve and toxicant-challenged conditions were tested. In naïve mice deficient in 5-LOX expression, a modest but significant reduction (18.0% reduction vs. wildtype (WT)) in striatal dopamine (DA) was detected (n=6-8 per genotype). A concomitant decline in striatal tyrosine hydroxylase (TH) enzyme was also revealed in null 5-LOX vs. WT mice (26.2%); however, no changes in levels of DA or TH immunoreactivity were observed in null 12/15-LOX vs. WT mice. When challenged with the selective dopaminergic toxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), WT mice showed a marked reduction in DA (31.9%) and robust astrocytic and microglial activation as compared to saline-treated animals. In contrast, null 5-LOX littermates demonstrated no significant striatal DA depletion or astrogliosis (as noted by Western blot analyses for glial acidic fibrillary protein (GFAP) immunoreactivity). In naïve null 12/15-LOX mice, no significant change in striatal DA values was observed compared to WT, and following MPTP treatment, the transgenics revealed striatal DA reduction similar to the challenged WT mice. Taken together, these data provide the first evidence that: (i) LOX isozymes are involved in the maintenance of normal dopaminergic function in the striatum and (ii) the 5- and 12/15-LOX isozymes contribute differentially to striatal vulnerability in response to neurotoxicant challenge.
Collapse
Affiliation(s)
- V P Chou
- Center for Health Sciences, SRI International, 333 Ravenswood Avenue, Menlo Park, CA 94025, USA.
| | | | | |
Collapse
|
7
|
Rink C, Khanna S. Significance of brain tissue oxygenation and the arachidonic acid cascade in stroke. Antioxid Redox Signal 2011; 14:1889-903. [PMID: 20673202 PMCID: PMC3078506 DOI: 10.1089/ars.2010.3474] [Citation(s) in RCA: 124] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The significance of the hypoxia component of stroke injury is highlighted by hypermetabolic brain tissue enriched with arachidonic acid (AA), a 22:6n-3 polyunsaturated fatty acid. In an ischemic stroke environment in which cerebral blood flow is arrested, oxygen-starved brain tissue initiates the rapid cleavage of AA from the membrane phospholipid bilayer. Once free, AA undergoes both enzyme-independent and enzyme-mediated oxidative metabolism, resulting in the formation of number of biologically active metabolites which themselves contribute to pathological stroke outcomes. This review is intended to examine two divergent roles of molecular dioxygen in brain tissue as (1) a substrate for life-sustaining homeostatic metabolism of glucose and (2) a substrate for pathogenic metabolism of AA under conditions of stroke. Recent developments in research concerning supplemental oxygen therapy as an intervention to correct the hypoxic component of stroke injury are discussed.
Collapse
Affiliation(s)
- Cameron Rink
- Department of Surgery, The Ohio State University Medical Center, Columbus, Ohio 43210, USA
| | | |
Collapse
|
8
|
Li J, Wang H, Rosenberg PA. Vitamin K prevents oxidative cell death by inhibiting activation of 12-lipoxygenase in developing oligodendrocytes. J Neurosci Res 2009; 87:1997-2005. [PMID: 19235890 DOI: 10.1002/jnr.22029] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Oxidative mechanisms of injury are important in many neurological disorders. Developing oligodendrocytes (pre-OLs) are particularly sensitive to oxidative stress-mediated injury. We previously demonstrated a novel function of phylloquinone (vitamin K(1)) and menaquinone 4 (MK-4; a major form of vitamin K2) in protecting pre-OLs and immature neurons against glutathione depletion-induced oxidative damage (Li et al. [ 2003] J. Neurosci. 23:5816-5826). Here we report that vitamin K at nanomolar concentrations prevents arachidonic acid-induced oxidative injury to pre-OLs through blocking the activation of 12-lipoxygenase (12-LOX). Arachidonic acid metabolism is a potential source for reactive oxygen species (ROS) generation during ischemia and reperfusion. Exposure of pre-OLs to arachidonic acid resulted in oxidative cell death in a concentration-dependent manner. Administration of vitamin K (K(1) and MK-4) completely prevented the toxicity. Consistent with our previous findings, inhibitors of 12-LOX abolished ROS production and cell death, indicating that activation of 12-LOX is a key event in arachidonic acid-induced pre-OL death. Vitamin K(1) and MK-4 significantly blocked 12-LOX activation and prevented ROS accumulation in pre-OLs challenged with arachidonic acid. However, vitamin K itself did not directly inhibit 12-LOX enzymatic activity when assayed with purified 12-LOX in vitro. These results suggest that vitamin K, or likely its metabolites, acts upstream of activation of 12-LOX in pre-OLs. In summary, our data indicate that vitamin K prevents oxidative cell death by blocking activation of 12-LOX and ROS generation.
Collapse
Affiliation(s)
- Jianrong Li
- The F.M. Kirby Neurobiology Center, Children's Hospital Boston, Harvard Medical School, Boston, MA 02115, USA
| | | | | |
Collapse
|
9
|
Farooqui AA, Ong WY, Horrocks LA. Inhibitors of brain phospholipase A2 activity: their neuropharmacological effects and therapeutic importance for the treatment of neurologic disorders. Pharmacol Rev 2006; 58:591-620. [PMID: 16968951 DOI: 10.1124/pr.58.3.7] [Citation(s) in RCA: 236] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The phospholipase A(2) family includes secretory phospholipase A(2), cytosolic phospholipase A(2), plasmalogen-selective phospholipase A(2), and calcium-independent phospholipase A(2). It is generally thought that the release of arachidonic acid by cytosolic phospholipase A(2) is the rate-limiting step in the generation of eicosanoids and platelet activating factor. These lipid mediators play critical roles in the initiation and modulation of inflammation and oxidative stress. Neurological disorders, such as ischemia, spinal cord injury, Alzheimer's disease, multiple sclerosis, prion diseases, and epilepsy are characterized by inflammatory reactions, oxidative stress, altered phospholipid metabolism, accumulation of lipid peroxides, and increased phospholipase A(2) activity. Increased activities of phospholipases A(2) and generation of lipid mediators may be involved in oxidative stress and neuroinflammation associated with the above neurological disorders. Several phospholipase A(2) inhibitors have been recently discovered and used for the treatment of ischemia and other neurological diseases in cell culture and animal models. At this time very little is known about in vivo neurochemical effects, mechanism of action, or toxicity of phospholipase A(2) inhibitors in human or animal models of neurological disorders. In kainic acid-mediated neurotoxicity, the activities of phospholipase A(2) isoforms and their immunoreactivities are markedly increased and phospholipase A(2) inhibitors, quinacrine and chloroquine, arachidonyl trifluoromethyl ketone, bromoenol lactone, cytidine 5-diphosphoamines, and vitamin E, not only inhibit phospholipase A(2) activity and immunoreactivity but also prevent neurodegeneration, suggesting that phospholipase A(2) is involved in the neurodegenerative process. This also suggests that phospholipase A(2) inhibitors can be used as neuroprotectants and anti-inflammatory agents against neurodegenerative processes in neurodegenerative diseases.
Collapse
Affiliation(s)
- Akhlaq A Farooqui
- Department of Molecular and Cellular Biochemistry, The Ohio State University, 1645 Neil Avenue, Columbus, OH 43210-1218, USA
| | | | | |
Collapse
|
10
|
González-Santiago L, Suárez Y, Zarich N, Muñoz-Alonso MJ, Cuadrado A, Martínez T, Goya L, Iradi A, Sáez-Tormo G, Maier JV, Moorthy A, Cato ACB, Rojas JM, Muñoz A. Aplidin® induces JNK-dependent apoptosis in human breast cancer cells via alteration of glutathione homeostasis, Rac1 GTPase activation, and MKP-1 phosphatase downregulation. Cell Death Differ 2006; 13:1968-81. [PMID: 16543941 DOI: 10.1038/sj.cdd.4401898] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Aplidin is an antitumor agent in phase II clinical trials that induces apoptosis through the sustained activation of Jun N-terminal kinase (JNK). We report that Aplidin alters glutathione homeostasis increasing the ratio of oxidized to reduced forms (GSSG/GSH). Aplidin generates reactive oxygen species and disrupts the mitochondrial membrane potential. Exogenous GSH inhibits these effects and also JNK activation and cell death. We found two mechanisms by which Aplidin activates JNK: rapid activation of Rac1 small GTPase and downregulation of MKP-1 phosphatase. Rac1 activation was diminished by GSH and enhanced by L-buthionine (SR)-sulfoximine, which inhibits GSH synthesis. Downregulation of Rac1 by transfection of small interfering RNA (siRNA) duplexes or the use of a specific Rac1 inhibitor decreased Aplidin-induced JNK activation and cytotoxicity. Our results show that Aplidin induces apoptosis by increasing the GSSG/GSH ratio, a necessary step for induction of oxidative stress and sustained JNK activation through Rac1 activation and MKP-1 downregulation.
Collapse
Affiliation(s)
- L González-Santiago
- Instituto de Investigaciones Biomédicas 'Alberto Sols', Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, Arturo Duperier, 4, Madrid E-28029, Spain
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Kwon KJ, Jung YS, Lee SH, Moon CH, Baik EJ. Arachidonic acid induces neuronal death through lipoxygenase and cytochrome P450 rather than cyclooxygenase. J Neurosci Res 2005; 81:73-84. [PMID: 15931672 DOI: 10.1002/jnr.20520] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Arachidonic acid (AA) is released from membrane phospholipids during normal and pathologic processes such as neurodegeneration. AA is metabolized via lipoxygenase (LOX)-, cyclooxygenase (COX)-, and cytochrome P450 (CYP450)-catalyzed pathways. We investigated the relative contributions of these pathways in AA-induced neuronal death. Exposure of cultured cortical neurons to AA (50 microM) yielded significantly apoptotic neuronal death, which was attenuated greatly by LOX inhibitors (nordihydroguaiaretic acid, AA861, and baicalein), or CYP450 inhibitors (SKF525A and metyrapone), rather than COX inhibitors (indomethacin and NS398). AA (10 microM)-induced neurotoxicity was prevented by all kinds of inhibitors. Compared, the neurotoxic effects of three pathway metabolites, 12-hydroxyeicosatetraenoic acid (12-HETE), a major LOX metabolite, induced a significant neurotoxicity. AA also produced reactive oxygen species within 30 min, which was reduced by all inhibitors tested, including COX inhibitors, and AA neurotoxicity was abolished by the antioxidant Trolox. AA treatment also depleted glutathione levels; this depletion was reduced by the LOX or CYP450 inhibitors rather than by the COX inhibitors. Taken together, our data suggested that the LOX pathway likely plays a major role in AA-induced neuronal death with the modification of intracellular free radical levels.
Collapse
Affiliation(s)
- Kyoung Ja Kwon
- Department of Physiology, Ajou University School of Medicine, Suwon, Korea
| | | | | | | | | |
Collapse
|
12
|
Akiyama N, Shimma N, Takashiro Y, Hatori Y, Hirabayashi T, Horie S, Saito T, Murayama T. Decrease in cytosolic phospholipase A2α mRNA levels by reactive oxygen species via MAP kinase pathways in PC12 cells: effects of dopaminergic neurotoxins. Cell Signal 2005; 17:597-604. [PMID: 15683734 DOI: 10.1016/j.cellsig.2004.10.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2004] [Accepted: 10/11/2004] [Indexed: 11/28/2022]
Abstract
Excess production of reactive oxygen species (ROS), including H2O2, leads to neuronal death in pathological conditions. Although ROS stimulates alpha-type cytosolic phospholipase A2 (cPLA2alpha) activity, their role in cPLA2alpha expression has not been elucidated. We investigated the effect of ROS on cPLA2alpha mRNA levels and signaling pathways in rat pheochromocytoma PC12 cells. Treatment with H2O2 and xanthine-xanthine oxidase (X/XO) for 4 h decreased cPLA2alpha mRNA levels without changing the mRNA levels of other tested proteins. H2O2 and X/XO caused cell toxicity not after 4 h but 24 h after their addition. The H2O2-induced decrease in cPLA2alpha mRNA levels was inhibited in cells treated with N-acetyl-cysteine and selective inhibitors of mitogen-activated protein kinase (MAPK) pathways (extracellular signal-regulated kinase and p38 MAPK). Treatment with dopaminergic neurotoxins, including 1,2,3,4-tetrahydroisoquinoline (TIQ)-inducing ROS formation, decreased cPLA2alpha mRNA levels. These findings suggest that ROS decreases cPLA2alpha mRNA levels via MAPK pathways in PC12 cells.
Collapse
Affiliation(s)
- Nobuteru Akiyama
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan
| | | | | | | | | | | | | | | |
Collapse
|